Mineral lubricating oil containing alkali and alkaline earth metal salts of alkylated dibenzothiophene sulfonic acid



Patented Oct. 24, 1950 MINER L LUBRICATING OIL CONTAINING A KALI ANALKALI E EA H S LTS. ALKY ATED mBENZ PHENE SULFONIC ACID 7 Frederick P.Richter and Everett W. Fuller, Wood-'- bury, N. J., assigii'ors tosocony-Vacuuiii pil Company, Incorporated, a corporation of New York .NDrawing. Application June 24, 1 4

1 7 Serial No. 756,812

This invention relates to alkylated dibenzothiophene sul-fonic acids, tometal salts thereof, and to a method for preparing the same. Moreparticularly, the present invention is concerned with lubricating oilcompositions improved by incorporating therein a small proportionsu-fiicient to improve the properties thereof ofone or more of theaforesaid compounds.

In accordance with the present invention, it has been discovered thatdibenzothiophene can be alkylated under certain conditions by contactingthe same with an allryl halide in the presence of a Friedel-Crafts typecatalyst to produce alky-lateddibenzothiophenes. a

It has further been discovered that the alkyl dibenzothiophene producedas described above can be sulfonated by contact with a suitable Still-2fonating agent, such as chlorosulfonic acid, concentrated sulfuric acid,oleurn, and the like.

Still further, itv has been discovered that metal salts of the alkylateddibenzothiophene sul Qllic acid, produced as a result of the aforesaidreaction, can be prepared uponcontacting said acid with an inorganicsalt or hydroxide of the desired metal. It has been further foundthatcertain of said metal. salts,,notably those of the al;-

kali and the alkaline earth metals, are useful asmineral oiladditives-and, more particularly, are efiective as detergents in motorlubricating oils.

The compositions of this invention are prepared by using as astartingmaterial substantially pure dibenzothiophene or a crude product whichcontains. a major proportion of dibenzothiophene. This starting'materialis alkylated in accordance with the present invention by bring.-

ing the same into contact with an; alkylhalide,

and a Friedel-Crafts catalyst, preferably in the presence of an inertorganic solvent such as Stoddards solvent.

The orientation of the alkylxgroup in, dibenzothiophene has not beenestablished: with certainty. Indicationszare, however, thatwhenonly onehydrogen in. each molecule ofv dibenzothio phene is replaced by analkylradical, the en-. tering alkyl group occupies the 2- or 3-.position andthat when twohydrogens are replaced with alkyl" groups, the enteringradicalsoccupy the 25- and 8-positions'or the 3;- and '7-positions. Theorientation, however, does not. appear to be, of too great. significancein the practical synthesis of: oil additive composition prepared fromthe dibenzothiophenes soalkylated'.

The. initial ratio of alkyl halide todibenzo thiophene can be varied.over wide limits. andt-he degree. of: alkylation thus controlled tovyield-- 8 Claims. (01. 252%?) h mono-, di-, and polyalkylateddibenzothiophenes.

Generally, however, a ratio of l to 3 gram atoms of halogen, as combinedin the alkyl halide, per mole of dibenzothiophene has been found to bepreferable. Alkylating agents of lower halogen content tend to result ina reduced yield of the desired alky-l dibenzothiophene, while those ofhigher halogen contents, as a general rule, giveno added advantages andresult in undue con-i sumption of the alkyl halide. Monoand di-'alkyldib'enzothi-ophenes accordingly represent preferred embodiments ofthe invention.

It has been established, in accordance with this: invention, that thetemperature at which alkylation of dibenzothiophene is efiected is acritical feature of the reaction. At temperatures below about 20 C., thealkylation reaction becomes sosluggish that the yield of desired productis prac-- tically nil; while at temperatures above about C., a tarformationbecomes predominant, causing a substantial decrease in theyield of desired product. Accordingly, the temperature range of fromabout 20 C; to about 85 C. appears to be a critical factor inthesuccessful alkylation of dibenzothiophene. Particular preference isaccorded to temperatures in the range of from about 60 C. to about 85C., since under these conditions the reaction was found to pro-- ceed ata faster rate, and consequently as a practical matter, to yield agreater amount of alkyl ated dibenzothiophene per unit time as comparedwith lower temperatures in the operable range.

The use of an inert organic solvent, while not absolutely necessary, hasbeen found to be highly desirable in modifying the alkylation ofdibenzothiophene, causing a substantial decrease in the formation ofundesirable tar as the condensation reaction proceeds. Any of thecommonly employed organic solvents which are inert under the conditionsof reaction" may beemployed for this purpose. 7 Representative solventsinclude Stoddards solvent,,carbon disnlfide, and the like. In general,theprocessrjdescribed herein may be employed for the alkylation ofdibenzothiophene with any alk-yl'halide, However, when the sulfonatemetallic salts of the resulting alkylated dibenzothiophene are to beemployed as oil ad; ditives, alkylhalides of suiii'cient carbon chainlength to render the prepared compound soluble in petroleum oil arepreferred. For this, as well as economical reasons, the-use of alkylhalides of hydrocarbons in theparaifin wax range having from about 20 toabout 30 carbon atoms represents a preferred embodiment. of thisinvention. Such; alkyl halides.- havingzmolecular weights in excess ofabout 250 and having more than about 20 carbon atoms in their moleculesare well known. Chlorinated wax maybe considered as a preferred exampleof such compounds and, in particular, those waxes in which the degree ofchlorination has been so regulated that the final chlorinated waxgenerally contains between about and about 15 per cent'c'hlorine.

The alkylated dibenzothiophenes described above may, in accordance withthis invention, be sulfonated by dissolving in a suitable solvent andadding thereto a sulfonating agent such as chlorosulfonic acid.Concentrated sulfuric acid, oleum, or the like may also be used forsulfonating and may be employed directly. The ratio of sulfonating agentto alkyldibenzothiophene may be varied over a wide range to yieldproducts of various degrees of sulfonation. In general, however, a ratioof 1 to 2 moles of sulfonating agent per mole of alkyldibenzothiopheneis preferred. The addition of sulfonating'agent to the solution ofalkyldibenzothiophene usually is conducted at ordinary roomtemperatures, that is, between about 15 C. and about 30 C. Upon finaladdition of the sulfonating agent, the mixture is suitably heated underreflux for a period to insure complete reaction. The solvent employedmay then be recovered by distillation. The residue obtained fromsaiddistillation is an alkyldibenzothiophene sulfonicacid.

- In order to prepare metallic salts thereof, the alkyldibenzothiophenesulfonic acid, as prepared above is dissolved in a suitable solvent,such as a refined petroleum oil, and the solution of sulfonic acid isconverted to the desired metal salt by simple neutralization thereofwith a metal hydroxide, carbonate or other alkaline inorganic salt ofthe metal. Alternatively, synthesis of the desired metal salt may beaccomplished by metathesis of an alkali metal sulfonate prepared by oneof the above mentioned methodswith an inorganic halide of the desiredmetal.

The temperature at which the metal salt of alkyldibenzothiophenesulfonic-acid is prepared will generally be in therange of from about 50C. to about 200 C. and preferably between about 85 C. and about 150 C.-The reaction mixture is maintained at an elevated temperature in theabove range until all of the water of reaction is removed. During thisoperation, it is desirable but not necessary to bubble an inert dry gassuch as nitrogen through the mixture in order to hasten the removal ofsaid water. The resulting mixture is then suitably filtered through aclarifying agent, such as .a filtering clay, to yield a petroleum oilsolution of a metal alkyldibenzothiophene sulfonate.

The above described procedure may be employed in synthesizing any of themetal salts having the general formula:

. soar drogen atom or an alkyl radical in the paraffin wax having achain ofto 30 carbon atoms.

The metal alkyldibenzothiophene sulfonates .described above have beenfound to be particularly useful in lubricating compositions where theybehave as detergents in maintaining the cleanliness of an engine.

These materials may be incorporated in any lubricating compositionranging from gasoline and kerosene to heavy gear oil, petroleum wax, andpetrolatum. They may also be used with similar lubricating compositionsderived from other animal, mineral, or vegetable sources, or preparedsynthetically. Such lubricating compositions may contain any otherdesired addition agent or combination of addition agents which may beadded for the purpose of effecting the same improvement or otherimprovements in that composition. Ordinarily, the new compositionsdescribed above will be added to mineral oil fractions in amountsranging from about 0.1 to about 5 per cent but may be added in amounts.-up to 10 per cent in some instances. Those; of,- the new products whichare sufiiciently soluble in oil may be marketed in the form of oilconcentrates, in which the percentage of the new products is greatly inexcess of that which is desired in the finallubricating composition, forexample, quantities up to about 50-per cent by weight.

Further details and advantages of this invention will be apparent fromthe following illustra'-' tive examples: 5:

Example 1 H Petroleum wax of A. S. T.' M. melting point of 125 F. waschlorinated by introducing chlorine gas at about F. until 12 per cent byweight of chlorine was adsorbed therein. 596.6 parts by weight of thechlorowax so obtained were slowly added to a mixture of 184 parts byweight of dibenzothiophene, 596.6 parts'by weight of Stoddard solvent,and 30 parts by weight of anhydrous aluminum chloride maintained at atemperature of 60C. The temperature was allowed togradually rise duringthe addition of the chlorowax to 75-85 C., in which range it was heldduring the alkylation. The mixture was agitated for aperiod of 4 hoursin this temperature range; after which time the'active evolution ofhydrogen chloride had practically ceased. To the cooled alkylationmixture; 500 volumes of 20 per cent aqueous hydrochloric acid wereslowly added and the resulting'mixture was heated to a temperature of100 C. to hasten the separation of the mixture into' organic and aqueouslayersi' After said separation was efiected', the mixture was cooled andthe aqueous. layer was drawn off and discarded. The remaining organicIayer Was washed with water, filtered, and the-solvent distilled offunder vacuum. x-Ihe dark green residue consisted of 706 parts byweight-of? a diwaxdibenzothiophene having a sulfur-content of 4.1 percent, the calculated sulfur content being'4'.0

percent. 1 e l I Two hundred parts by Weight. of the diwaxdibenzothiophene as prepared above. were dissolved in 400 volumes ofchloroform. Forty-one and two tenths parts by weightofxchlorosulfonic'acid were addedd'ropwise to the, resulting solution atroom temperature. When the-addition of sulfonating agent wascomplete,.the mixture washeatedunder reflux for a periodof 2 :hours tocomplete the reaction. The chloroform was their recovered bydistillation and .theiresidue was identified: gasa .diwaxdibnzothiophenesulfonic acid having a neutralization number of :81, the theoreticalneutralization number lbeing 82.

. Example 2' The diwaxdibenzothiophene sulfonic acid as prepared inExample 1 was diluted 'with 400 parts by weight of an SAE 30 gradesolvent-refined petroleum oiland 9'7 parts by weight of barium hydroxideoctahydrate were added. The result ing' mixture was held at atemperature-of 85 C; for a'period of 1 hour, raised gradually to 100 C.for 1 hour and finally increased to 150 C.. where it was held until allof the water in the reaction mixture had been removed. This requiredmaintaining the reaction mixture at the temperature of 150 C. for anadditional hour. Duringthis operation -a steady stream of -dry. nitrogengas was passed "through the mixture inorder to facilitate the removal ofthe water. The resulting hot oilsolution was then filtered throughHi-Flo (a clay of the activated montmorillonite 'typ represented'by theideal formula: 7 Ahsnomornz nmo wherein n is an integer). The filtrateobtained from said filtration consisted of a petroleum oil solution ofbarium diwaxdibenzothiophene sul-' fonate having a barium content of 4.1per cent and a sulfur content of 2.6 per cent.

Example 3 The diwaxdibenzothiophene sulfonic acid prepared as in Example1 was reacted with magnesium hydroxide, in the same manner as describedExample 4 A mixture consisting of 230 grams of a diwaxdibenzothiophenesulfonic acid, 23 grams of sodium hydroxide dissolved in 200 c. c. ofmethanol and 400 grams of a solvent-refined SAE 30 grade motor oil washeated under reflux with efiicient stirring for 2 hours. The methanoland water of reaction were then removed by distillation with a steadystream of dry nitrogen gas passing through the mixture until thetemperature reached 150 C. Final traces of methanol and water wereremoved by maintaining the temperature of the mixture at 150 C. with acurrent of dry nitrogen gas passingtherethrough. The resulting hot oilsolution was passed through a filtering clay at a temperature of about95-100 C. in order to remove unreacted sodium hydroxide and otherinsoluble impurities. The product so obtained consisted of 520 grams ofa clear oil solution of sodium diwaxdibenzothiophene sulfonatecontaining 1.4 per cent sodium and 3.2 per cent sulfur.

The above described metallic salts are effective as detergents in motorlubricating oils, as is demonstrated by the following test: Blends weremade in a SAE 30 grade solvent-refined motor oil containing 0.75 percent by weight of an antioxidant additive, consisting of the reactionproduct of pinene and phosphorus pentasulfide similar to that describedin Example 3 of U. S. Patent 2 381377., The ifollowin'g blends wereprepared: A. Oil plus'0.'75 per centantioxidant. v B. 0ilp1us10.75 percent antioxidant plus15'per cent of the 'above'described bariumdiwaxdibenzothiophenesulfonate. C.' Oil-plus 0.75 percent antioxidantplus 2 fp'er "enter the above described magnesium diwax'dibenz'othiophene sulfonate. D. Oil plus 0.75 per cent antioxidantplus 2'per cent of the abov described sodium"d'iwax Cleanliness Rating Il '20 Hrs. '60 Hrs. realms F Blend D 74 68 55 The above results showthat the alkali and alkaline earth metal salts of diwaxdibenzothiophenesulfonic acid are effective additives in improving the characteristicsof lubricating oils.

The above described lubricating compositions are, of course, merelyillustrative of those contemplated by the present invention.Antioxidants other than the pinene-phosphorus pentasulfide reactionproduct may be used. Likewise, various other improving agents may bepresent in the oil blend, such as V. I. agents, pour point depressants,oiliness agents, and the like.

We claim:

1. A lubricating oil composition that comprises a mineral oil fractionand a small proportion sufficient to improve the detergent propertiesthereof of an alkaline earth metal salt of an alkylated dibenzothiophenesulfonic acid in which the sulfonic acid radical is attached directly toa benzene nucleus, said acid having an alkyl group of between about 20and about 30 carbon atoms.

2. A lubricating oil composition that comprises a mineral oil fractionand a small proportion sufficient to improve the detergent propertiesthereof of an alkali metal salt of an alkylated dibenzothiophenesulfonic acid in which the sulfonic acid radical is attached directly toa benzene nucleus, said acid having an alkyl group of between about 20and about 30 carbon atoms.

3. A lubricating oil composition that comprises a mineral oil fractionand a small proportion sufficient to improve the properties thereof of acompound selected from the group consisting of the alkali and alkalineearth metal salts of an alkylated dibenzothiophene sulfonic acid inwhich the sulfonic acid radical is attached directly to a benzenenucleus, said acid having an alkyl group of between about 20 and 30carbon atoms.

4. A lubricating oil composition that comprises a mineral oil fractionand a small proportion sufiicient to improve the detergent propertiesthereof of a sodium salt of an alkylated dibenzothiophene sulfonic acidin which the sulfonic acldx'z'adlcal is attached' dirtljitd {Benzenenucleus, said acid having. ,an alkyl group of be; tween about 20 andabout 30, carbn atoms; i 'i'f A lubricating oil composition thatcomprises a mineral oil fraction and a. small proportion sufi'icient toimprove the detergent. properties thereof of -a' magnesium salt "of analky lated dibe'nzothioph'enev sulfonic, acid inwhich'ltlie sulfonicacid radical is attached directly to, a ben- Zene nucleus, said acidhaving an alkyl'gr'oup of between about 20 and about 30 carbonatoms.

6. A lubricating oil composition that cornprlses a mineral'oil fractionand a small proportion suflicient to improve the detergent "propertiesthereof of a barium salt of an alkylated dibenzothiophene sulfonic acidin which the sulfonic' acid radical is attached directly'to a benzenenucleus; said acid having an alkyl group of between about 20 and about30 carbon atoms. I 3

7. A lubricating oil composition thatcompr'ises a mineral oil fractionand between about-0.1 and and about 5 per cent by weight of acompoundslected from the group consisting of the alkali and alkalineearth metal salts of an alkylated dibenzothiophene sulfonic acid inwhich the sulfonic acid radical is attached directly to a benbetweenabout REFERENCES CITED The following references are of record in th fileof'this patent:

' UNITED STATES PATENTS Number Name Date 1,471,150 Dziewonski Oct. 16,1923 1,996,334 Hessle Apr. 2, 19 2,160,293 Shoemaker May 30, 19892,361,805 Wilson Oct. 31, 1944 McNab Apr. 15, 1947 Certificate ofCorrection Patent No. 2,527,334 October 24, 1950 FREDERICK P. RICHTER ETAL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows:

Column 6, line 64, before the Word properties insert detergent;

and that the said Letters Patent should be read as corrected "above, sothat the same may conform to the record of the case in the PatentOffice.

Signed and sealed this 8th day of May, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant C'ommz'ssz'oner of Patents.

6. A LUBRICATING OIL COMPOSITION THAT COMPRISES A MINERAL OIL FRACTIONAND A SMALL PROPORTION SUFFICIENT TO IMPROVE THE DETERGENT PROPERTIESTHEREOF OF A BARIUM SALT OF AN ALKYLATED DIBENZOTHIOPHENE SULFONIC ACIDIN WHICH THE SULFONIC ACID RADICAL IS ATTACHED DIRECTLY TO A BENZENENUCLEUS SAID ACID HAVING AN ALKYL GROUP OF BETWEEN ABOUT 20 AND ABOUT 30CARBON ATOMS.